Containers are commonly used to transport cargo with ships, airplanes and trucks. Made of strong material, like steel, the rigid structure has doors on one side by which the container is secured when closed. Conversely, the container is loaded and unloaded when the doors are opened.
In particular, in the military setting a wide variety of logistical support systems are now containerized in order to speed troop deployments. For military applications, structural requirements are significant in terms of acceptable cargo load, acceleration (G forces) and dry weight. Full size containers must be able to carry 8000 pounds of cargo at 3.5 G acceleration in addition to a safety factor of 1.5.
Moreover, in at least one configuration, the container can be air lifted by helicopter or a crane when fully loaded. The container must also be carried by a fork lift. The container must therefore be capable of sustaining the forces applied in different directions (i.e. pulling, supporting).
The container must be dismountable by a limited number of people, without tools, within minutes. The parts of the container must also be interchangeable from one container to another.
On the logistic side, transport requirements are often asymmetric, with more cargo being shipped in one direction than the other. This creates logistical problems because the return transportation of empty containers is often inefficient and costly. Although the containers are lighter when empty, the load volume remains unchanged.
Collapsible containers have been used to decrease the load volume used by the empty containers on the return voyage. Prior collapsible container designs include containers that are disassembled and shipped as a group of components, and containers with folding parts which allow the structure of the container to be folded in a manner that reduces the volume used.
Existing collapsible containers lack strength and durability. The inclusion of folding parts results in a considerably complex structure. Hinges and joints are susceptible to material fatigue and failure and thus increase the risk of dealing with a defective container during critical situations.
The transport of empty containers in a disassembled configuration poses additional problems as the disassembled components require suitable packaging.
A collapsible container that meets the various requirements and avoids the disadvantages detailed above is therefore desirable. It is also desirable to have a container, reducible in volume, easy to manufacture, easy to use, and is reliable.